Method and system for flexible FM tuning

ABSTRACT

A method and system for flexible FM tuning are provided and may include tuning to a particular frequency within a range of FM channels based on an IF frequency that includes an integer multiple of the channel spacing between neighboring allocated FM channels within the range of FM channels, offset by at most one-half the channel spacing. The method may further include determining whether the particular frequency comprises an on frequency channel, utilizing a frequency error that is based on the IF frequency. A local oscillator frequency may be selected for the tuning based on the frequency offset. An intermediate frequency (IF) channel may be generated utilizing the particular frequency and the selected local oscillator frequency. The generated IF channel may be between neighboring channels selected from the range of FM channels. The frequency error may be determined for the particular frequency within the range of FM channels.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

The application makes reference to, claims priority to, and claims thebenefit of U.S. Provisional Application Ser. No. 60/685,239 filed on May26, 2005.

This application also makes reference to:

U.S. application Ser. No. 11/176,417, filed on Jul. 7, 2005;

U.S. application Ser. No. ______ (Attorney Docket No. 16663US02) filedon even date herewith;

U.S. application Ser. No. ______ (Attorney Docket No. 17107US02) filedon even date herewith;

U.S. application Ser. No. ______ (Attorney Docket No. 17108US02) filedon even date herewith;

U.S. application Ser. No. ______ (Attorney Docket No. 17109US02) filedon even date herewith;

U.S. application Ser. No. ______ (Attorney Docket No. 17110US02) filedon even date herewith;

U.S. application Ser. No. ______ (Attorney Docket No. 17113US02) filedon even date herewith;

U.S. application Ser. No. ______ (Attorney Docket No. 17115US02) filedon even date herewith; and

U.S. application Ser. No. ______ (Attorney Docket No. 17116US02) filedon even date herewith.

Each of the above stated applications is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to Bluetooth and FMcommunication technologies. More specifically, certain embodiments ofthe invention relate to a method and system for flexible FM tuning.

BACKGROUND OF THE INVENTION

With the popularity of portable electronic devices and wireless devicesthat support audio applications, there is a growing need to provide asimple and complete solution for audio communications applications. Forexample, some users may utilize Bluetooth-enabled devices, such asheadphones and/or speakers, to allow them to communicate audio data withtheir wireless handset while freeing to perform other activities. Otherusers may have portable electronic devices that may enable them to playstored audio content and/or receive audio content via broadcastcommunication, for example.

However, integrating multiple audio communication technologies into asingle device may be costly. Combining a plurality of differentcommunication services into a portable electronic device or a wirelessdevice may require separate processing hardware and/or separateprocessing software. Moreover, coordinating the reception and/ortransmission of data to and/or from the portable electronic device or awireless device may require significant processing overhead that mayimpose certain operation restrictions and/or design challenges. Forexample, a handheld device such as a cellphone that incorporatesBluetooth and Wireless LAN may pose certain coexistence problems causedby the close proximity of the Bluetooth and WLAN transceivers.Furthermore, simultaneous use of a plurality of radios in a handheld mayresult in significant increases in power consumption. Power being aprecious commodity in most wireless mobile devices, combining devicessuch as a cellular radio, a Bluetooth radio and a WLAN radio requirescareful design and implementation in order to minimize battery usage.Additional overhead such as sophisticated power monitoring and powermanagement techniques are required in order to maximize battery life.

A portable electronic device or a wireless device may be adapted toreceive audio content via broadcast communication when used in differentgeographic locations. However, due to different frequency channelplanning regulations adopted by different countries, processing of audiocontent received via broadcast communication is challenging. Forexample, the placement of the image frequency at a certain location maybe optimal for one country but may not be optimal for another. In thisregard, detection of the image channel is difficult when the portableelectronic device or the wireless device is utilized in differentcountries. During signal processing, image rejection (IMR) techniquesmay be used to suppress the image channel. However, image rejectiontechniques are limited and may only provide limited scope of rejectionof the image channel.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for flexible FM tuning, substantiallyas shown in and/or described in connection with at least one of thefigures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a block diagram of an exemplary FM transmitter thatcommunicates with handlheld devices that utilize a single chip withintegrated Bluetooth and FM radios, in accordance with an embodiment ofthe invention.

FIG. 1 B is a block diagram of an exemplary FM receiver thatcommunicates with handlheld devices that utilize a single chip withintegrated Bluetooth and FM radios, in accordance with an embodiment ofthe invention.

FIG. 1C is a block diagram of an exemplary single chip with integratedBluetooth and FM radios that supports FM processing and an externaldevice that supports Bluetooth processing, in accordance with anembodiment of the invention.

FIG. 1D is a block diagram of an exemplary single chip with integratedBluetooth and FM radios and an external device that supports Bluetoothand FM processing, in accordance with an embodiment of the invention.

FIG. 1E is a block diagram of an exemplary single chip with multipleintegrated radios that supports radio data processing, in accordancewith an embodiment of the invention.

FIG. 1F is a block diagram of an exemplary single chip with integratedBluetooth and FM radios that supports multiple interfaces, in accordancewith an embodiment of the invention.

FIG. 1G is a block diagram of an exemplary single chip with integratedBluetooth and FM radios that supports interfacing with a handsetbaseband device and a coexistent wireless LAN (WLAN) radio, inaccordance with an embodiment of the invention.

FIG. 2A is a block diagram of an exemplary single chip that supportsBluetooth and FM operations with an external FM transmitter, inaccordance with an embodiment of the invention.

FIG. 2B is a block diagram of an exemplary single chip that supportsBluetooth and FM operations with an integrated FM transmitter, inaccordance with an embodiment of the invention.

FIG. 2C is a flow diagram that illustrates exemplary steps forprocessing received data in a single chip with integrated Bluetooth andFM radios, in accordance with an embodiment of the invention.

FIG. 2D is a flow diagram that illustrates exemplary steps forprocessing FM data via the Bluetooth core in a single chip withintegrated Bluetooth and FM radios, in accordance with an embodiment ofthe invention.

FIG. 2E is a flow diagram that illustrates exemplary steps forconfiguring a single chip with integrated Bluetooth and FM radios basedon the mode of operation, in accordance with an embodiment of theinvention.

FIG. 3 is a block diagram of an exemplary FM core and PTU for processingRDS and digital audio data, in accordance with an embodiment of theinvention.

FIG. 4A is a graph illustrating an exemplary on frequency channel and acorresponding image channel, in accordance with an embodiment of theinvention.

FIG. 4B is a graph illustrating selection of an intermediate frequency(IF) utilizing an offset, in accordance with an embodiment of theinvention.

FIG. 4C is a flow diagram that illustrates exemplary steps for flexibleFM tuning, in accordance with an embodiment of the invention.

FIG. 5 is a block diagram illustrating an exemplary front-end portion ofan FM radio receiver, in accordance with an embodiment of the invention.

FIG. 6 is a block diagram illustrating an exemplary high-side andlow-side injection in a front-end portion of an FM radio receiver, inaccordance with an embodiment of the invention.

FIG. 7 is a block diagram illustrating I/Q phase and amplitudeadjustment in a front-end portion of an FM radio receiver, in accordancewith an embodiment of the invention.

FIG. 8 is a flow diagram that illustrates exemplary steps for processingof signals, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method and systemfor flexible FM tuning. Aspects of the method and system may comprisetuning to a particular frequency within a range of FM channels based onan IF frequency that includes an integer multiple of the channel spacingbetween neighboring allocated FM channels within the range of FMchannels, offset by at most one-half the channel spacing. The method mayfurther include determining whether the particular frequency comprisesan on frequency channel utilizing a frequency error. The frequency errormay be based on the IF frequency. In the United States for example, therange of FM channels is 88-108 MHz and the channel spacing is 100 KHz.Accordingly, the offset may be less than 50 KHz.

A local oscillator frequency may be selected for the tuning based on thefrequency offset. An intermediate frequency (IF) channel may begenerated utilizing the particular frequency and the selected localoscillator frequency. The generated IF channel may be betweenneighboring channels selected from the range of FM channels. Thefrequency error may be determined for the particular frequency withinthe range of FM channels. The frequency error for the particularfrequency may be determined utilizing a DC offset at the output of theFM demodulator. Signal strength information for a plurality of imagechannels corresponding to a plurality of on frequency channels selectedfrom the range of FM channels may be stored. Tuning to at least one ofthe plurality of on frequency channels may be based on the stored signalstrength information.

FIG. 1A is a block diagram of an exemplary FM transmitter thatcommunicates with handlheld devices that utilize a single chip withintegrated Bluetooth and FM radios, in accordance with an embodiment ofthe invention. Referring to FIG. 1A, there is shown an FM transmitter102, a cellular phone 104 a, a smart phone 104 b, a computer 104 c, andan exemplary FM and Bluetooth-equipped device 104 d. The FM transmitter102 may be implemented as part of a radio station or other broadcastingdevice, for example. Each of the cellular phone 104 a, the smart phone104 b, the computer 104 c, and the exemplary FM and Bluetooth-equippeddevice 104 d may comprise a single chip 106 with integrated Bluetoothand FM radios for supporting FM and Bluetooth data communications. TheFM transmitter 102 may enable communication of FM audio data to thedevices shown in FIG. 1A by utilizing the single chip 106. Each of thedevices in FIG. 1A may comprise and/or may be communicatively coupled toa listening device 108 such as a speaker, a headset, or an earphone, forexample.

The cellular phone 104 a may be enabled to receive an FM transmissionsignal from the FM transmitter 102. The user of the cellular phone 104 amay then listen to the transmission via the listening device 108. Thecellular phone 104 a may comprise a “one-touch” programming feature thatenables pulling up specifically desired broadcasts, like weather,sports, stock quotes, or news, for example. The smart phone 104 b may beenabled to receive an FM transmission signal from the FM transmitter102. The user of the smart phone 104 b may then listen to thetransmission via the listening device 108.

The computer 104 c may be a desktop, laptop, notebook, tablet, and aPDA, for example. The computer 104 c may be enabled to receive an FMtransmission signal from the FM transmitter 102. The user of thecomputer 104 c may then listen to the transmission via the listeningdevice 108. The computer 104 c may comprise software menus thatconfigure listening options and enable quick access to favorite options,for example. In one embodiment of the invention, the computer 104 c mayutilize an atomic clock FM signal for precise timing applications, suchas scientific applications, for example. While a cellular phone, a smartphone, computing devices, and other devices have been shown in FIG. 1A,the single chip 106 may be utilized in a plurality of other devicesand/or systems that receive and use Bluetooth and/or FM signals. In oneembodiment of the invention, the single chip Bluetooth and FM radio maybe utilized in a system comprising a WLAN radio. U.S. application Ser.No. ______ (Attorney Docket No. 17116US02), filed on even date herewith,discloses a method and system comprising a single chip Bluetooth and FMradio integrated with a wireless LAN radio, and is hereby incorporatedherein by reference in its entirety.

FIG. 1B is a block diagram of an exemplary FM receiver that communicateswith handheld devices that utilize a single chip with integratedBluetooth and FM radios, in accordance with an embodiment of theinvention. Referring to FIG. 1B, there is shown an FM receiver 110, thecellular phone 104 a, the smart phone 104 b, the computer 104 c, and theexemplary FM and Bluetooth-equipped device 104 d. In this regard, the FMreceiver 110 may comprise and/or may be communicatively coupled to alistening device 108. A device equipped with the Bluetooth and FMtransceivers, such as the single chip 106, may be able to broadcast itsrespective signal to a “deadband” of an FM receiver for use by theassociated audio system. For example, a cellphone or a smart phone, suchas the cellular phone 104 a and the smart phone 104 b, may transmit atelephone call for listening over the audio system of an automobile, viausage of a deadband area of the car's FM stereo system. One advantagemay be the universal ability to use this feature with all automobilesequipped simply with an FM radio with few, if any, other external FMtransmission devices or connections being required.

In an exemplary embodiment of the invention, the FM receiver 110 may beadapted to provide flexible FM tuning functionalities. In this regard,the FM receiver 110 may utilize an FM receiver front-end which may beadapted to locate image channels for different channel spacing schemes.For example, based on the geographic location of the FM receiver 110, anadjustable intermediate frequency (IF) may be utilized so that the imagechannel may be characterized by a determined offset. During tuning to aparticular frequency, a frequency error and/or a received signalstrength indicator (RSSI) may be measured for the particular frequency.If the measured frequency error indicates a presence of an offset or ifa detected offset is higher than a threshold value, the particularfrequency may comprise an image channel. If the particular frequencycomprises an image channel, the image channel may be rejected byutilizing a different injection point within the receiver front-end.

In another example, a computer, such as the computer 104 c, may comprisean MP3 player or another digital music format player and may broadcast asignal to the deadband of an FM receiver in a home stereo system. Themusic on the computer may then be listened to on a standard FM receiverwith few, if any, other external FM transmission devices or connections.While a cellular phone, a smart phone, and computing devices have beenshown, a single chip that combines a Bluetooth and FM transceiver and/orreceiver may be utilized in a plurality of other devices and/or systemsthat receive and use an FM signal.

FIG. 1C is a block diagram of an exemplary single chip with integratedBluetooth and FM radios that supports FM processing and an externaldevice that supports Bluetooth processing, in accordance with anembodiment of the invention. Referring to FIG. 1C, there is shown asingle chip 112 a that supports Bluetooth and FM radio operations and anexternal device 114. The single chip 112 a may comprise an integratedBluetooth radio 116, an integrated FM radio 118, and an integratedprocessor 120. The Bluetooth radio 116 may comprise suitable logic,circuitry, and/or code that enable Bluetooth signal communication viathe single chip 112 a. In this regard, the Bluetooth radio 116 maysupport audio signals or communication. The FM radio may comprisesuitable logic, circuitry, and/or code that enable FM signalcommunication via the single chip 112 a.

The integrated processor 120 may comprise suitable logic, circuitry,and/or code that may enable processing of the FM data received by the FMradio 118. Moreover, the integrated processor 120 may enable processingof FM data to be transmitted by the FM radio 118 when the FM radio 118comprises transmission capabilities. The external device 114 maycomprise a baseband processor 122. The baseband processor 122 maycomprise suitable logic, circuitry, and/or code that may enableprocessing of Bluetooth data received by the Bluetooth radio 116.Moreover, the baseband processor 122 may enable processing of Bluetoothdata to be transmitted by the Bluetooth radio 116. In this regard, theBluetooth radio 116 may communicate with the baseband processor 122 viathe external device 114. The Bluetooth radio 116 may communicate withthe integrated processor 120.

In an exemplary embodiment of the invention, the FM radio 118 maycomprise an FM receiver, which may be adapted to provide flexible FMtuning functionalities. The FM receiver within the FM radio 118 mayutilize an FM receiver front-end which may enable locating imagechannels for different channel spacing schemes. For example, based onthe geographic location of the FM receiver 110, an adjustableintermediate frequency (IF) may be utilized so that the image channelmay be characterized by a determined offset. During tuning to aparticular frequency, a frequency error and/or a received signalstrength indicator (RSSI) may be measured for the particular frequency.If the measured frequency error indicates a presence of an offset or ifa detected offset is higher than a threshold value, the particularfrequency may comprise an image channel. If the particular frequencycomprises an image channel, the image channel may be rejected byutilizing a different injection point within the receiver front-end.

FIG. 1D is a block diagram of an exemplary single chip with integratedBluetooth and FM radios and an external device that supports Bluetoothand FM processing, in accordance with an embodiment of the invention.Referring to FIG. 1D, there is shown a single chip 112 b that supportsBluetooth and FM radio operations and an external device 114. The singlechip 112 b may comprise the Bluetooth radio 116 and the FM radio 118.The Bluetooth radio 116 and/or the FM radio 118 may be integrated intothe single chip 112 b. The external device 114 may comprise a basebandprocessor 122. The baseband processor 122 may comprise suitable logic,circuitry, and/or code that may enable processing of Bluetooth datareceived by the Bluetooth radio 116 and/or processing of Bluetooth datato be transmitted by the Bluetooth radio 116. In this regard, theBluetooth radio 116 may communicate with the baseband processor 122 viathe external device 114. Moreover, the baseband processor 122 maycomprise suitable logic, circuitry, and/or code that may enableprocessing of the FM data received by the FM radio 118. The basebandprocessor 122 may enable processing FM data to be transmitted by the FMradio 118 when the FM radio 118 comprises transmission capabilities. Inthis regard, the FM radio 118 may communicate with the basebandprocessor 122 via the external device 114.

FIG. 1E is a block diagram of an exemplary single chip with multipleintegrated radios that supports radio data processing, in accordancewith an embodiment of the invention. Referring to FIG. 1E, there isshown a single chip 130 that may comprise a radio portion 132 and aprocessing portion 134. The radio portion 132 may comprise a pluralityof integrated radios. For example, the radio portion 132 may comprise acell radio 140 a that supports cellular communications, a Bluetoothradio 140 b that supports Bluetooth communications, an FM radio 140 cthat supports FM communications, a global positioning system (GPS) 140 dthat supports GPS communications, and/or a wireless local area network(WLAN) 140 e that supports communications based on the IEEE 802.11standards. The FM radio 140 c may be similar to the FM radio 118 in FIG.1C and may provide the flexible FM tuning functionalities as describedherein.

The processing portion 134 may comprise at least one processor 136, amemory 138, and a peripheral transport unit (PTU) 140. The processor 136may comprise suitable logic, circuitry, and/or code that enableprocessing of data received from the radio portion 132. In this regard,each of the integrated radios may communicate with the processingportion 134. In some instances, the integrated radios may communicatewith the processing portion 134 via a common bus, for example. Thememory 138 may comprise suitable logic, circuitry, and/or code thatenable storage of data that may be utilized by the processor 136. Inthis regard, the memory 138 may store at least a portion of the datareceived by at least one of the integrated radios in the radio portion132. Moreover, the memory 138 may store at least a portion of the datathat may be transmitted by at least one of the integrated radios in theradio portion 132. The PTU 140 may comprise suitable logic, circuitry,and/or code that may enable interfacing data in the single chip 130 withother devices that may be communicatively coupled to the single chip130. In this regard, the PTU 140 may support analog and/or digitalinterfaces.

FIG. 1F is a block diagram of an exemplary single chip with integratedBluetooth and FM radios that supports multiple interfaces, in accordancewith an embodiment of the invention. Referring to FIG. 1F, there isshown a single chip 150 that supports Bluetooth and FM radiocommunications. The single chip 150 may comprise a processor and memoryblock 152, a PTU 154, an FM control and input-output (IO) block 156, aBluetooth radio 158, a Bluetooth baseband processor 160, and an FM andradio data system (RDS) and radio broadcast data system (RDBS) radio162. A first antenna or antenna system 166 a may be communicativelycoupled to the Bluetooth radio 158. A second antenna or antenna system166 b may be communicatively coupled to the FM and RDS/RBDS radio 162.The FM and RDS/RBDS radio 162 may comprise an FM receiver, which mayprovide flexible FM tuning functionalities as described herein.

The processor and memory block 152 may comprise suitable logic,circuitry, and/or code that may enable control, management, dataprocessing operations, and/or data storage operations, for example. ThePTU 154 may comprise suitable logic, circuitry, and/or code that mayenable interfacing the single chip 150 with external devices. The FMcontrol and IO block 156 may comprise suitable logic, circuitry, and/orcode that may enable control of at least a portion of the FM andRDS/RBDS radio 162. The Bluetooth radio 158 may comprise suitable logic,circuitry, and/or code that may enable Bluetooth communications via thefirst antenna 166 a. The FM and RDS/RBDS radio 162 may comprise suitablelogic, circuitry, and/or code that may enable FM, RDS, and/or RBDS datacommunication via the second antenna 166 b. The Bluetooth basebandprocessor 160 may comprise suitable logic, circuitry, and/or code thatmay enable processing of baseband data received from the Bluetooth radio158 or baseband data to be transmitted by the Bluetooth radio 158.

The PTU 154 may support a plurality of interfaces. For example, the PTU154 may support an external memory interface 164 a, a universalasynchronous receiver transmitter (UART) and/or enhanced serialperipheral interface (eSPI) interface 164 b, a general purposeinput/output (GPIO) and/or clocks interface 164 c, a pulse-codemodulation (PCM) and/or an inter-IC sound (I²S) interface 164 d, aninter-integrated circuit (I²C) bus interface 164 e, and/or an audiointerface 164 f.

FIG. 1G is a block diagram of an exemplary single chip with integratedBluetooth and FM radios that supports interfacing with a handsetbaseband device and a coexistent wireless LAN (WLAN) radio, inaccordance with an embodiment of the invention. Referring to FIG. 1G,there is shown a single chip 172, a handset baseband block 170, a bandpass filter 174, a first antenna or antenna system 178 a, a matchingcircuit 176, a second antenna or antenna filter 178 b, and a WLAN radio180. The single chip 172 may be substantially similar to the single chip150. In this instance, the single chip 172 may comprise suitable logic,circuitry, and/or code that may enable coexistent operation with theWLAN radio 180 via the coexistence interface 186.

The single chip 172 may communicate Bluetooth data via the BPF 174 andthe first antenna 178 a. The single chip 172 may also communicate FMdata via the matching circuit 176 and the second antenna 178 b. Thesingle chip 172 may coordinate Bluetooth data communication in thepresence of WLAN channels by communicating with the WLAN radio 180 viathe coexistence interface 186. The single chip 172 may comprise an FMreceiver, which may provide flexible FM tuning functionalities asdescribed herein.

The single chip 172 may transfer data to the handset baseband block 170via at least one interface, such as a PCM/I2S interface 182 a, aUART/eSPI interface 182 b, a I²C interface 182 c, and/or and analogaudio interface 182 d. The single chip 172 and the handset basebandblock 170 may also communicate via at least one control signal. Forexample, the handset baseband block 170 may generate a clock signal,ref_clock, 184 a, a wake signal, host_wake 184 c, and/or a reset signal184 f that may be transferred to the single chip 172. Similarly, thesingle chip 172 may generate a clock request signal, clock_req, 184 b, aBluetooth wake signal, BT_wake, 184 d, and/or an FM interrupt requestsignal, FM IRQ, 184 e that may be transferred to the handset basebandblock 170. The handset baseband block 170 may comprise suitable logic,circuitry, and/or code that may enable processing of at least a portionof the data received from the single chip 172 and/or data to betransferred to the single chip 172. In this regard, the handset basebandblock 170 may transfer data to the single chip 172 via at least oneinterface.

FIG. 2A is a block diagram of an exemplary single chip that supportsBluetooth and FM operations with an external FM transmitter, inaccordance with an embodiment of the invention. Referring to FIG. 2A,there is shown a single chip 200 that may comprise a processor system202, a peripheral transport unit (PTU) 204, a Bluetooth core 206, afrequency modulation (FM) core 208, and a common bus 201. An FMtransmitter 226 may be an external device to the single chip 200 and maybe communicatively coupled to the single chip 200 via the FM core 208,for example. The FM transmitter 226 may be a separate integrated circuit(IC), for example.

The processor system 202 may comprise a central processing unit (CPU)210, a memory 212, a direct memory access (DMA) controller 214, a powermanagement unit (PMU) 216, and an audio processing unit (APU) 218. TheAPU 218 may comprise a subband coding (SBC) codec 220. At least aportion of the components of the processor system 202 may becommunicatively coupled via the common bus 201.

The CPU 210 may comprise suitable logic, circuitry, and/or code that mayenable control and/or management operations in the single chip 200. Inthis regard, the CPU 210 may communicate control and/or managementoperations to the Bluetooth core 206, the FM core 208, and/or the PTU204 via a set of register locations specified in a memory map. Moreover,the CPU 210 may be utilized to process data received by the single chip200 and/or to process data to be transmitted by the single chip 200. TheCPU 210 may enable processing of data received via the Bluetooth core206, via the FM core 208, and/or via the PTU 204. For example, the CPU210 may enable processing of A2DP data and may then transfer theprocessed A2DP data to other components of the single chip 200 via thecommon bus 201. In this regard, the CPU may utilize the SBC codec 220 inthe APU 218 to encode and/or decode A2DP data, for example. The CPU 210may enable processing of data to be transmitted via Bluetooth core 206,via the FM core 208, and/or via the PTU 204. The CPU 210 may be, forexample, an ARM processor or another embedded processor core that may beutilized in the implementation of system-on-chip (SOC) architectures.

The CPU 210 may time multiplex Bluetooth data processing operations andFM data processing operations. In this regard, the CPU 210 may performeach operation by utilizing a native clock, that is, Bluetooth dataprocessing based on a Bluetooth clock and FM data processing based on anFM clock. The Bluetooth clock and the FM clock may be distinct and maynot interact. The CPU 210 may gate the FM clock and the Bluetooth clockand may select the appropriate clock in accordance with the timemultiplexing scheduling or arrangement. When he CPU 210 switches betweenBluetooth operations and FM operations, at least certain statesassociated with the Bluetooth operations or with the FM operations maybe retained until the CPU 210 switches back.

For example, in the case where the Bluetooth function is not active andis not expected to be active for some time, the CPU 210 may run on aclock derived from the FM core 208. This may eliminate the need to bringin a separate high-speed clock when one is already available in the FMcore 208. In the case where the Bluetooth core 206 may be active, forexample when the Bluetooth is in a power-saving mode that requires it tobe active periodically, the processor may chose to use a clock derivedseparately from the FM core 208. The clock may be derived directly froma crystal or oscillator input to the Bluetooth core 206, or from a phaselocked loop (PLL) in the Bluetooth core 206. While this clocking schememay provide certain flexibility in the processing operations performedby the CPU 210 in the single chip 200, other clocking schemes may alsobe implemented.

The CPU 210 may also enable configuration of data routes to and/or fromthe FM core 208. For example, the CPU 210 may configure the FM core 208so that data may be routed via an I²S interface or a PCM interface inthe PTU 204 to the analog ports communicatively coupled to the PTU 204.

The CPU 210 may enable tuning, such as flexible tuning, and/or searchingoperations in Bluetooth and/or FM communication by controlling at leasta portion of the Bluetooth core 206 and/or the FM core 208. For example,the CPU 210 may generate at least one signal that tunes the FM core 208to a certain frequency to determine whether there is a station at thatfrequency. When a station is found, the CPU 210 may configure a path forthe audio signal to be processed in the single chip 200. When a stationis not found, the CPU 210 may generate at least one additional signalthat tunes the FM core 208 to a different frequency to determine whethera station may be found at the new frequency.

Searching algorithms may enable the FM core 208 to scan up or down infrequency from a presently tuned channel and stop on the next channelwith received signal strength indicator (RSSI) above a threshold. Thesearch algorithm may be able to distinguish image channels. The choiceof the IF frequency during search is such that an image channel may havea nominal frequency error of 50 kHz, which may be used to distinguishthe image channel from the “on” channel. The search algorithm may alsobe able to determine if a high side or a low side injection providesbetter receive performance, thereby allowing for a signal quality metricto be developed for this purpose. One possibility to be investigated ismonitoring the high frequency RSSI relative to the total RSSI. The IFmay be chosen so that with the timing accuracy that a receiver may beenabled to provide, the image channels may comprise a frequency errorthat is sufficiently large to differentiate the image channels from theon channel.

The CPU 210 may enable a host controller interface (HCI) in Bluetooth.In this regard, the HCI provides a command interface to the basebandcontroller and link manager, and access to hardware status and controlregisters. The HCI may provide a method of accessing the Bluetoothbaseband capabilities that may be supported by the CPU 210.

The memory 212 may comprise suitable logic, circuitry, and/or code thatmay enable data storage. In this regard, the memory 212 may be utilizedto store data that may be utilized by the processor system 202 tocontrol and/or manage the operations of the single chip 200. The memory212 may also be utilized to store data received by the single chip 200via the PTU 204 and/or via the FM core 208. Similarly, the memory 212may be utilized to store data to be transmitted by the single chip 200via the PTU 204 and/or via the FM core 208. The DMA controller 214 maycomprise suitable logic, circuitry, and/or code that may enable transferof data directly to and from the memory 212 via the common bus 201without involving the operations of the CPU 210.

The PTU 204 may comprise suitable logic, circuitry, and/or code that mayenable communication to and from the single chip 200 via a plurality ofcommunication interfaces. In some instances, the PTU 204 may beimplemented outside the single chip 200, for example. The PTU 204 maysupport analog and/or digital communication with at least one port. Forexample, the PTU 204 may support at least one universal series bus (USB)interface that may be utilized for Bluetooth data communication, atleast one secure digital input/output (SDIO) interface that may also beutilized for Bluetooth data communication, at least one universalasynchronous receiver transmitter (UART) interface that may also beutilized for Bluetooth data communication, and at least one I²C businterface that may be utilized for FM control and/or FM and RDS/RBDSdata communication. The PTU 204 may also support at least one PCMinterface that may be utilized for Bluetooth data communication and/orFM data communication, for example.

The PTU 204 may also support at least one inter-IC sound (I²S)interface, for example. The I²S interface may be utilized to send highfidelity FM digital signals to the CPU 210 for processing, for example.In this regard, the I²S interface in the PTU 204 may receive data fromthe FM core 208 via a bus 203, for example. Moreover, the I²S interfacemay be utilized to transfer high fidelity audio in Bluetooth. Forexample, in the A2DP specification there is support for wideband speechthat utilizes 16 kHz of audio. In this regard, the I²S interface may beutilized for Bluetooth high fidelity data communication and/or FM highfidelity data communication. The I²S interface may be a bidirectionalinterface and may be utilized to support bidirectional communicationbetween the PTU 204 and the FM core 208 via the bus 203. The I²Sinterface may be utilized to send and receive FM data from externaldevices such as coder/decoders (CODECs) and/or other devices that mayfurther process the I²S data for transmission, such as localtransmission to speakers and/or headsets and/or remote transmission overa cellular network, for example.

The Bluetooth core 206 may comprise suitable logic, circuitry, and/orcode that may enable reception and/or transmission of Bluetooth data.The Bluetooth core 206 may comprise a Bluetooth transceiver 229 that mayperform reception and/or transmission of Bluetooth data. In this regard,the Bluetooth core 206 may support amplification, filtering, modulation,and/or demodulation operations, for example. The Bluetooth core 206 mayenable data to be transferred from and/or to the processor system 202,the PTU 204, and/or the FM core 208 via the common bus 201, for example.

The FM core 208 may comprise suitable logic, circuitry, and/or code thatmay enable reception and/or transmission of FM data. The FM core 208 maycomprise an FM receiver 222 and a local oscillator (LO) 227. The FMreceiver 222 may comprise an analog-to-digital (A/D) converter 224. TheFM receiver 222 may support amplification, filtering, and/ordemodulation operations, for example. The LO 227 may be utilized togenerate a reference signal that may be utilized by the FM core 208 forperforming analog and/or digital operations. The FM core 206 may enabledata to be transferred from and/or to the processor system 202, the PTU204, and/or the Bluetooth core 206 via the common bus 201, for example.Moreover, the FM core 208 may receive analog FM data via the FM receiver222. The FM receiver 222 may provide flexible FM tuning functionalitiesas described herein.

The A/D converter 224 in the FM receiver 222 may be utilized to convertthe analog FM data to digital FM data to enable processing by the FMcore 208. The FM core 208 may also enable the transfer of digital FMdata to the FM transmitter 226. The FM transmitter 226 may comprise adigital-to-analog (D/A) converter 228 that may be utilized to convertdigital FM data to analog FM data to enable transmission by the FMtransmitter 226. Data received by the FM core 208 may be routed out ofthe FM core 208 in digital format via the common bus 201 and/or inanalog format via the bus 203 to the I²S interface in the PTU 204, forexample.

The FM core 208 may enable radio transmission and/or reception atvarious frequencies, such as, 400 MHz, 900 MHz, 2.4 GHz and/or 5.8 GHz,for example. The FM core 208 may also support operations at the standardFM band comprising a range of about 76 MHz to 108 MHz, for example.

The FM core 208 may also enable reception of RDS data and/or RBDS datafor in-vehicle radio receivers. In this regard, the FM core 208 mayenable filtering, amplification, and/or demodulation of the receivedRDS/RBDS data. The RDS/RBDS data may comprise, for example, a trafficmessage channel (TMC) that provides traffic information that may becommunicated and/or displayed to an in-vehicle user.

Digital circuitry within the FM core 208 may be operated based on aclock signal generated by dividing down a signal generated by the LO227. The LO 227 may be programmable in accordance with the variouschannels that may be received by the FM core 208 and the divide ratiomay be varied in order to maintain the digital clock signal close to anominal value.

The RDS/RBDS data may be buffered in the memory 212 in the processorsystem 202. The RDS/RBDS data may be transferred from the memory 212 viathe I²C interface when the CPU 210 is in a sleep or stand-by mode. Forexample, the FM core 208 may post RDS data into a buffer in the memory212 until a certain level is reached and an interrupt is generated towake up the CPU 210 to process the RDS/RBDS data. When the CPU 210 isnot in a sleep mode, the RDS data may be transferred to the memory 212via the common bus 201, for example.

Moreover, the RDS/RBDS data received via the FM core 208 may betransferred to any of the ports communicatively coupled to the PTU 204via the HCI scheme supported by the single chip 200, for example. TheRDS/RBDS data may also be transferred to the Bluetooth core 206 forcommunication to Bluetooth-enabled devices.

In one exemplary embodiment of the invention, the single chip 200 mayreceive FM audio data via the FM core 208 and may transfer the receiveddata to the Bluetooth core 206 via the common bus 201. The Bluetoothcore 206 may transfer the data to the processor system 202 to beprocessed. In this regard, the SBC codec 220 in the APU 218 may performSBC coding or other A2DP compliant audio coding for transportation ofthe FM data over a Bluetooth A2DP link. The processor system 202 mayalso enable performing continuous variable slope delta (CVSD)modulation, log pulse code modulation (Log PCM), and/or other Bluetoothcompliant voice coding for transportation of FM data on Bluetoothsynchronous connection-oriented (SCO) or extended SCO (eSCO) links. TheBluetooth-encoded FM audio data may be transferred to the Bluetooth core206, from which it may be communicated to another device that supportsthe Bluetooth protocol. The CPU 210 may be utilized to control and/ormanage the various data transfers and/or data processing operations inthe single chip 200 to support the transmission of FM audio data via theBluetooth protocol.

Moreover, when Bluetooth data is received, such as A2DP, SCO, eSCO,and/or MP3, for example, the Bluetooth core 206 may transfer thereceived data to the processor system 202 via the common bus 201. At theprocessor system 202, the SBC codec 220 may decode the Bluetooth dataand may transfer the decoded data to the FM core 208 via the common bus201. The FM core 208 may transfer the data to the FM transmitter 226 forcommunication to an FM receiver in another device.

In another exemplary embodiment of the invention, the single chip 200may operate in a plurality of modes. For example, the single chip 200may operate in one of an FM-only mode, a Bluetooth-only mode, and anFM-Bluetooth mode. For the FM-only mode, the single chip 200 may operatewith a lower power active state than in the Bluetooth-only mode or theFM-Bluetooth mode because FM operation in certain devices may have alimited source of power. In this regard, during the FM-only mode, atleast a portion of the operation of the Bluetooth core 206 may bedisabled to reduce the amount of power used by the single chip 200.Moreover, at least a portion of the processor system 202, such as theCPU 210, for example, may operate based on a divided down clock from aphase locked-loop (PLL) in the FM core 208. In this regard, the PLL inthe FM core 208 may utilize the LO 227, for example.

Moreover, because the code necessary to perform certain FM operations,such as tuning and/or searching, for example, may only require theexecution of a few instructions in between time intervals of, forexample, 10 ms, the CPU 210 may be placed on a stand-by or sleep mode toreduce power consumption until the next set of instructions is to beexecuted. In this regard, each set of instructions in the FM operationscode may be referred to as a fragment or atomic sequence. The fragmentsmay be selected or partitioned in a very structured manner to optimizethe power consumption of the single chip 200 during FM-only modeoperation. In some instances, fragmentation may also be implemented inthe FM-Bluetooth mode to enable the CPU 210 to provide more processingpower to Bluetooth operations when the FM core 208 is carrying outtuning and/or searching operations, for example.

FIG. 2B is a block diagram of an exemplary single chip that supportsBluetooth and FM operations with an integrated FM transmitter, inaccordance with an embodiment of the invention. Referring to FIG. 2B,there is shown the single chip 200 as described in FIG. 2A with the FMtransmitter 226 integrated into the FM core 208. In this regard, the FMcore 208 may support FM reception and/or transmission of FM data. The FMtransmitter 226 may utilize signals generated based on the referencesignal generated by the LO 227. The FM core 208 may enable transmissionof data received via the PTU 204 and/or the Bluetooth core 206, forexample. The exemplary implementation of the single chip 200 asdescribed in FIG. 2B may support FM reception and/or transmission andBluetooth reception and/or transmission.

FIG. 2C is a flow diagram that illustrates exemplary steps forprocessing received data in a single chip with integrated Bluetooth andFM radios, in accordance with an embodiment of the invention. Referringto FIGS. 2A and 2C, in step 232, after start step 230, the FM core 208or the Bluetooth core 206 may receive data. For example, the FM core 208may receive FM data via the FM receiver 222 and the Bluetooth core 206may receive Bluetooth data via the Bluetooth transceiver 229. In step234, the received data may be transferred to the processor system 202via the common bus 201 for processing. The received data may betransferred to the memory 212 by the DMA controller 214, for example. Insome instances, the processor system 202 may then transfer the data tothe PTU 204, for example. The received data may be transferred to theprocessing system 202 in accordance with the time multiplexing scheduleor arrangement provided by the processing system 202. In step 236, theprocessor system 202 may time multiplex the processing of FM data andthe processing of Bluetooth data. For example, when Bluetooth data isbeing processed, FM data may not be transferred to the processing system202 or may be transferred and stored in the memory 212 until FMprocessing is enabled. When the processing system 202 has completedprocessing the Bluetooth data, the FM data may be transferred to theprocessing system 202 for FM processing. Similarly, when FM data isbeing processed, Bluetooth data may not be transferred to the processingsystem 202 or may be transferred and stored in the memory 212 untilBluetooth processing is enabled. When the processing system 202 hascompleted processing the FM data, the Bluetooth data may be transferredto the processing system 202 for Bluetooth processing. After step 236,the process may proceed to end step 238.

FIG. 2D is a flow diagram that illustrates exemplary steps forprocessing FM data via the Bluetooth core in a single chip withintegrated Bluetooth and FM radios, in accordance with an embodiment ofthe invention. Referring to FIGS. 2A and 2D, after start step 250, instep 252, the FM core 208 may receive FM data via the FM receiver 222.In step 254, the FM core 208 may transfer the FM data to the Bluetoothcore 206 via the common bus 201. In step 256, the Bluetooth core 206 maytransfer the FM data received from the FM core 208 to the processorsystem 202 via the common bus 201. In step 258, the processor system 202may perform Bluetooth processing operations, such as encoding forexample, to the FM data received from the Bluetooth core 206. In step260, the Bluetooth core 206 may receive the processed FM data. In step262, the Bluetooth core 206 may transfer the processed FM data to atleast one Bluetooth-enable device via the Bluetooth transceiver 229.

An illustrative instance where the exemplary steps described in FIG. 2Dmay occur is when a handset is enabled to receive FM data and thehandset may be enabled to operate with a Bluetooth headset. In thisregard, the handset may receive the FM audio signal via the FM core 208and may process the received signal for transfer to the headset via theBluetooth core 206.

FIG. 2E is a flow diagram that illustrates exemplary steps forconfiguring a single chip with integrated Bluetooth and FM radios basedon the mode of operation, in accordance with an embodiment of theinvention. Referring to FIG. 2E, after start step 270, in step 272, Whena single chip with integrated Bluetooth and FM radios operates in anFM-only mode, the process may proceed to step 284. In step 284, the FMcore 208 may be configured for operation and at least portions of theBluetooth core 206 may be disabled. In step 286, FM data received and/orFM data to be transmitted may be processed in the processor system 202without need for time multiplexing.

Returning to step 272, when the single chip is not operating in theFM-only mode, the process may proceed to step 274. In step 274, when thesingle chip is operating in the Bluetooth-only mode, the process mayproceed to step 280. In step 280, the Bluetooth core 206 may beconfigured for operation and at least portions of the FM core 208 may bedisabled. In step 282, Bluetooth data received and/or Bluetooth data tobe transmitted may be processed in the processor system 202 without needfor time multiplexing.

Returning to step 274, when the single chip is not operating in theBluetooth-only mode, the process may proceed to step 276. In step 276,the Bluetooth core 206 and the FM core 208 may be configured foroperation. In step 278, Bluetooth data and/or FM data may be processedin the processor system 202 in accordance with time multiplexingschedule or arrangement.

FIG. 3 is a block diagram of an exemplary FM core and PTU for processingRDS and digital audio data, in accordance with an embodiment of theinvention. Referring to FIG. 3, there is shown a more detailed portionof the single chip 200 described in FIGS. 2A-2B. The portion of thesingle chip 200 shown in FIG. 3 comprises the FM core 208, the memory212, the CPU 210, and the common bus 201. Also shown are portions of thePTU 204 comprising an interface multiplexer 310, a universal peripheralinterface (UPI) 304, a bus master interface 302, a digital audiointerface controller 306, an I²S interface block 308, and an I2Cinterface block 312. The FM core 208 may comprise a rate adaptor 314, abuffer 316, an FM/MPX demodulator and decoder 317, an RDS/RBDSdemodulator and decoder 318, and a control registers block 322. Narrowlyspaced hashed arrows as illustrated by the flow arrow 332 show the flowof digital audio data. Broadly spaced hashed arrows as illustrated bythe flow arrow 334 show the flow of RDS/RBDS data. Clear or blankarrows, as illustrated by the dual flow arrow 336, show the flow ofcontrol data.

The FM/MPX demodulator and decoder 317 may comprise suitable logic,circuitry, and/or code that may enable processing of FM and/or FM MPXstereo audio, for example. The FM/MPX demodulator and decoder 317 maydemodulate and/or decode audio signals that may be transferred to therate adaptor 314. The FM/MPX demodulator and decoder 317 may demodulateand/or decode signals that may be transferred to the RDS/RBDSdemodulator and decoder 318. The rate adaptor 314 may comprise suitablelogic, circuitry, and/or code that may enable controlling the rate ofthe FM data received from the FM/MPX demodulator and decoder 317. Therate adaptor 314 may comprise suitable logic, circuitry, and/or codethat may enable controlling the rate of the FM data received by the FMcore 208. The rate adaptor 314 may adapt the output sampling rate of theaudio paths to the sampling clock of the host device or the rate of aremote device when a digital audio interface is used to transport the FMdata. An initial rough estimate of the adaptation fractional change maybe made and the estimate may then refined by monitoring the ratio ofreading and writing rates and/or by monitoring the level of the audiosamples in the output buffer. The rate may be adjusted in a feedbackmanner such that the level of the output buffer is maintained. The rateadaptor 314 may receive a strobe or pull signal from the digital audiointerface controller 306, for example. Audio FM data from the rateadaptor 314 may be transferred to the buffer 316.

The buffer 316 may comprise suitable logic, circuitry, and/or code thatmay enable storage of digital audio data. The buffer 316 may receive astrobe or pull signal from the digital audio interface controller 306,for example. The buffer 316 may transfer digital audio data to thedigital audio interface controller 306. The digital audio interfacecontroller 306 may comprise suitable logic, circuitry, and/or code thatmay enable the transfer of digital audio data to the bus masterinterface 302 and/or the I²S interface block 308. The I²S interface 308may comprise suitable logic, circuitry, and/or code that may enabletransfer of the digital audio data to at least one devicecommunicatively coupled to the single chip. The I²S interface 308 maycommunicate control data with the bus master interface 302.

The FM demodulator 317 may comprise suitable circuitry, logic, and/orcode and may enable demodulation of signals received by the FM core 208.The RDS/RBDS demodulator and decoder 318 may comprise suitable logic,circuitry, and/or code that may enable processing of RDS/RBDS data fromthe FM/MPX demodulator and decoder 317. The RDS/RBDS demodulator anddecoder 318 may provide further demodulation and/or decoding to datareceived from the FM/MPX demodulator and decoder 317. The output of theRDS/RBDS decoder 318 may be transferred to the interface multiplexer310. The interface multiplexer 310 may comprise suitable logic,circuitry, and/or code that may enable the transfer of RDS/RBDS data tothe UPI 304 and/or the I²C interface block 312. In this regard, the UPI304 may generate a signal that indicates to the interface multiplexer310 the interface to select. The I²C interface 312 may comprise suitablelogic, circuitry, and/or code that may enable transfer of the RDS/RBDSdata to at least one device communicatively coupled to the single chip.The I²C interface 312 may also communicate control data between externaldevices to the single chip and the interface multiplexer 310. In thisregard, the interface multiplexer 310 may communicate control databetween the I²C interface 312, the UPI 304, and/or the control registersblock 322 in the FM core 208. The control registers block 322 maycomprise suitable logic, circuitry, and/or code that may enable thestorage of register information that may be utilized to control and/orconfigure the operation of at least portions of the FM core 208.

The UPI 304 may comprise suitable logic, circuitry, and/or code that mayenable the transfer of digital audio data to the bus master interface302 from the interface multiplexer 310. The UPI 304 may also enable thecommunication of control data between the bus master interface 302 andthe interface multiplexer 310. The bus master interface 302 may comprisesuitable logic, circuitry, and/or code that may enable communication ofcontrol data, digital audio data, and/or RDS/RBDS data between theportions of the PTU 204 shown in FIG. 3 and the common bus 201. The busmaster interface 302 may transfer digital audio data and/or RDS/RBDSdata to the common bus 201. The RDS/RBDS data may be transferred to thememory 212, for example. In some instances, the RDS/RBDS data may betransferred to the memory 212 when the CPU 210 is in a stand-by or sleepmode. The bus master interface 302 may push RDS/RBDS data into a bufferin the memory 212 or may pull RDS/RBDS data from a buffer in the memory212, for example. The digital audio data may be transferred to the CPU210 for processing, for example. The CPU 210 may generate and/or receivecontrol data that may be communicated with the PTU 204 and/or the FMcore 208 via the common bus 201.

In one embodiment of the invention, the single chip with integrated FMand Bluetooth radios may implement a search algorithm that collects andstores data during scanning of the FM band. The single chip maydetermine whether there is music or speech in a detected channel.Moreover, the single chip may enable searching and finding 10 of thestrongest stations, for example, and may rank them.

In another embodiment of the invention, the single chip with integratedFM and Bluetooth radios may implement a search algorithm where thesearches may be done based on specific criteria such as type of stationor type of music, for example. The single chip may characterize each ofthe stations found based on the search.

In another embodiment of the invention, the single chip with integratedFM and Bluetooth radios may enable turning OFF a voltage regulator tothe FM radio when in BT-only mode or turning OFF voltage regulators tothe Bluetooth radio and the FM radio when both Bluetooth and FM are notbeing used, for example. In another embodiment of the invention, thesingle chip with integrated FM and Bluetooth radios may enable extendingthe battery life in a handheld device by requiring that the single chipdoes not consume power until configured by the host. Moreover, there maynot be a load on the system until the chip is powered down and/or thechip may not draw any current when powered down.

In another embodiment of the invention, the single chip with integratedFM and Bluetooth radios may enable a digital filter that may combinede-emphasis, bass, and/or treble. The digital filter may have aprogrammable audio bandwidth, for example. In another embodiment of theinvention, the single chip with integrated FM and Bluetooth radios mayenable a power amplifier dynamical bypass for Class 1 systems. Inanother embodiment of the invention, the single chip with integrated FMand Bluetooth radios may enable an antenna with an adjustable centerfrequency.

In another embodiment of the invention, the single chip with integratedFM and Bluetooth radios may enable Bluetooth coexistence with WLAN. Inthis regard, coexistence may be supported when radiation of energy isnot greater than a certain threshold. In some cases, such threshold maybe 90 dBm, for example. The coexistence may be implemented to minimizethe amount of energy that flows from the Bluetooth radio to the WLANradio, for example. In this regard, the single chip may utilize aguilty-by-association technique in order to identify WLAN interferingchannels in the vicinity of a Bluetooth device. Because WLAN channelsmay deteriorate very rapidly in the presence of Bluetooth communication,the guilty-by-association technique may enable a fast determination oridentification of which adaptive frequency hopping (AFH) channels toblock in order to limit the effect of Bluetooth communication on WLANchannels. Channel measurement statistics may be collected in ‘bins’ of NMHz each where N=2,3,4, etc and condemn the entire bin as bad if any Kof the channels in the bin was measured as bad. An example may be whenK=1. Condemnation of the entire bin as bad, that is,guilty-by-association, may increase both the reliability as well asspeed with a WLAN channels of contiguous 20˜22 MHz that may be blockedout in the AFH channel map. The use of techniques that modify the AFHchannel map need not be limited to instances when a Bluetooth radio andan FM radio are integrated into a single chip. Modification of the AFHchannel map may be applied to instances when Bluetooth applications arein coexistent operation with WLAN applications.

The WLAN interfering channels may be detected by utilizing channelmeasurement statistics such as received signal strength indicator (RSSI)energy measurements and/or packet error rate (PER) measurements. PERmeasurements may include missing a packet due to synchronization errors,cyclic redundancy check (CRC) errors in decoding the header, and/or CRCerrors in decoding the payload, for example. These measurements may beperformed during the Bluetooth frame duration (1.25 ms) on the currentBluetooth channel or on channels different from the current Bluetoothchannel.

In another embodiment of the invention, the single chip with integratedFM and Bluetooth radios may enable a low noise FM phase-locked loop(PLL) that may minimize the 32 KHz clock noise and/or the large phasenoise that may occur. In this regard, the FM PLL may utilize a narrowloop bandwidth, for example.

In another embodiment of the invention, the single chip with integratedFM and Bluetooth radios may disable at least a portion of the analogcircuitry in the FM radio and/or the Bluetooth radio when performingdigital processing. Disabling analog circuitry provides a reduction inthe amount of power consumed by the single chip.

In another embodiment of the invention, the single chip with integratedFM and Bluetooth radios may be enabled to support high definition (HD)radio systems. In HD radio systems, the broadcasters may utilize digitalsignals to transmit existing analog AM and FM signals. In this regard,the analog AM and FM signals may be transmitted simultaneously and theuse of digital channels may result in higher quality audio and a morerobust signal. In first generation HD radio systems, services such asMain Program Service or Station Reference Service may be provided. Otherservices that may be supported for HD radio in the single chip may berequests for audio presentation of news, weather, entertainment, and/orstocks, for example. Additional services may comprise navigationalproducts or applications, such as traffic information, for example,time-shifted listening, mobile commerce and advertisement,Internet-based broadcasts, and/or reading services for the visuallyimpaired.

In an exemplary embodiment of the invention, image channel detection inan FM receiver front-end may be significantly improved via flexibletuning by utilizing a programmable IF frequency. For example, when an FMchannel is changed, a tuning algorithm may first be utilized todistinguish image frequency channels from “on frequency” channels, ordesired channels. In this regard, the initial channel spacing used inthe tuning process may be chosen such that the image frequency fallsbetween the minimum channel spacing, for example. Furthermore, the imagechannel may show a frequency error due to the fact that the imagefrequency falls between the minimum channel spacing. The frequency errormay then be used to distinguish image channels from on frequencychannels. In another embodiment of the invention, a frequency error mayalso be measured by measuring a DC offset at the output of an FMdemodulator, where the DC offset may be proportional to the frequencyerror.

FIG. 4A is a graph illustrating an exemplary on frequency channel and acorresponding image channel, in accordance with an embodiment of theinvention. Referring to FIG. 4A, the graph 400 illustrates the locationof a desired frequency channel 402 and a corresponding image channel404. The desired frequency channel 402 may be centered at theintermediate frequency (IF) and the corresponding image channel 404 maybe centered at frequency (−IF). In instances where the image channel 404is detected, it may be rejected utilizing image rejection (IMR)topologies, such as quadrature mixing followed by an image rejectingcomplex band-pass filtering. In this regard, the image channel 404 maybe rejected by an IMR measure of 406. In an exemplary embodiment of theinvention, a dynamically adjustable IF may be utilized to determinewhether a particular frequency channel, such as channel 404, comprise animage channel. A frequency error may be detected in channel 404 and itmay be determined that channel 404 comprises an image channel. Ininstances when a higher IF frequency is selected, the distance delta f408, or Δf, may increase.

If delta f 408 increases, the image channel 404 may move away, or mayshift to the left. Consequently, if the image channel 404 is detectedand shifted by a determined offset, the image channel signal level 404may be further suppressed by utilizing, for example, a complex imagerejecting band pass filter. In another embodiment of the invention,after the image channel 404 is detected, high-side, low-side rejectionmay be utilized to flip the image channel 404 from one side to theother. In this regard, a high and low local oscillator frequency inconjunction with swapping the I and Q signals, may be utilized with thedesired frequency channel 402 to flip the current image channel 404 onthe other side of the desired signal 402. If the signal energy in theupper image frequency channel is lower in magnitude compared to thesignal energy in the lower image channel, the upper image channel wouldbe selected to achieve an improved signal-to-interferer ratio after theband-pass filtering.

FIG. 4B is a graph illustrating selection of an intermediate frequency(IF) utilizing an offset, in accordance with an embodiment of theinvention. Referring to FIG. 4B, the graph 420 illustrates channelspacing between a plurality of channels and selection of IF frequencyfor purposes of determining whether a particular frequency comprises animage channel. For example, channel spacing of N*100 kHz may be utilizedfor image channel detection, where N is an integer. Graph 420illustrates channel spacing between neighboring channels (k−2)*100 kHz,(k−1)*100 kHz, k*100 kHz, (k+1)*100 kHz, and (k+2)*100 kHz, where k maybe an integer. Frequency channel 425 may be located at k*100 kHz and acorresponding image channel 423 may be located at (−k)*100 kHz. The IFfrequency for channel 425 may be IF1 430 and the corresponding IFfrequency for the image channel 423 may be −IF1 432. Distance delta f1426 may be 2*IF1.

In an exemplary embodiment of the invention, the IF frequency IF1 430 ofchannel 425 may be adjusted so that it includes an integer multiple ofthe channel spacing between FM channels in the vicinity of channel 425,offset by at most one-half the channel spacing. For example, the channelspacing of channels (k−2)*100 kHz, (k−1)*100 kHz, k*100 kHz, (k+1)*100kHz, and (k+2)*100 kHz may be 100 kHz and the offset 424 for IF1 430 maybe selected as one-quarter the channel spacing, or 25 kHz. As a resultof the offset 424, the image channel 423 may be shifted by an offset422, which is also 25 kHz. In this regard, delta f1 426, which is thedistance between the on frequency channel 425 and the image channel 423,may be increased by 50 kHz. The resulting new delta f2 428 may be thesum of the new IF frequency IF2 434 of the offset channel 425 and thecorresponding IF frequency (−IF2) 436 of the offset image channel 423.

The resulting delta f2 428 may be equal to K×100 kHz +50 kHz and the IFfrequency IF2 434 may be equal to M×100 kHz +25 kHz. In this regard, afrequency error may be detected for channel 423 and it may be determinedwhether channel 423 is an image channel based on the determinedfrequency error of the received signal. If the frequency error is morethan, for example, 25 kHz, then it may be determined that channel 423comprises an image channel. If it is determined that channel 423comprises an image channel, the delta f2 428 may be further changed sothat the image channel 423 may be filtered, for example. Alternatively,the image channel 423 may be flipped by utilizing a high-side orlow-side injection point.

Even though channel spacing of N*100 kHz is utilized for flexible tuningand image channel detection, the present invention may not be solimited. Other channel spacing may also be utilized so that an IFfrequency may include an integer multiple of the channel spacing betweenneighboring allocated FM channels offset by at most one-half channelspacing. In another embodiment of the invention, flexible tuning may beused in performing a search up-band and/or down-band on an FM radio, forexample. Tuning information may be obtained during the search and ahistory of frequency channels and corresponding image channels may bekept to help in search algorithms. In some instances, information onwhich channels are on-channels and which are image channels may bestored. In another embodiment of the invention, changing the IFfrequency and delta f may be performed dynamically during tuning of FMchannels.

FIG. 4C is a flow diagram that illustrates exemplary steps for flexibleFM tuning, in accordance with an embodiment of the invention. Referringto FIG. 4C, at 450, an FM radio may be initially tuned to channel f0specified using (N+0.25)*IF frequency relative to channels spacing,where N may be an integer. At 452, a received signal strength indicator(RSSI) and/or a frequency error may be measured for the tuned channel.At 454, it may be determined whether the absolute value of the frequencyerror is greater than a threshold value. If the absolute value of thefrequency error is greater than the threshold value, at 456, it may bedetermined that the current channel is an image channel. If the absolutevalue of the frequency error is not greater than the threshold value, at458, it may be determined that the current channel is an on frequencychannel, or a desired channel. At 460, RSSI may be measured at channelsf(0+2N+1), f(0+2N), f(0−2N), and f(0−2N−1) by adjusting the IF frequencyand/or the injection point. At 462, the on frequency channel, or thedesired channel may be tuned so that the image channel lies on the imagechannel with the lowest RSSI. In instances when a channel has RDS,program information (PI) code associated with the RDS may be utilized todetermine country information. In this regard, an optimum image channelsetting may be determined based on the country information within the PIcode.

In another embodiment of the invention, an FM receiver, such as the FMreceiver 222 in FIG. 2A, may be utilized for an UP or DOWN channelsearch with a modified flexible tuning search algorithm. Since thesearch performed by the FM receiver may be sequential, the first 4N+2channels “on channel” RSSI may be gathered before making the decision onwhich frequency channel to select first. Moreover, an image frequencyand injection point may then be determined for the channel scanned 2N+1steps back with every new channel scanned. In this regard, an FM radiomay enable scanning UP or DOWN in frequency from a presently tunedchannel and stop on the next channel with RSSI above a threshold value,for example.

The search algorithm may be utilized for distinguishing image channelsand also strong channels that may cross the RSSI threshold value but maybe off in frequency. The selection of the IF frequency during the searchmay be such that an image channel may have a nominal frequency error ofat most half the channel spacing, such as 50 kHz, for example. In thisregard, the image channel may be distinguished from the desired onfrequency channel. The search algorithm may also be utilized fordetermining whether high-side or low-side injection may provide betterreceive performance, and a signal quality metric may be developed forthis purpose.

FIG. 5 is a block diagram illustrating an exemplary front-end portion ofan FM radio receiver, in accordance with an embodiment of the invention.Referring to FIG. 5, there is shown the frequency domain operation of aportion of an FM radio receiver front-end 501. In this regard, theoperation refers to a variable receiver (RX) intermediate frequency(IF). The FM radio receiver front-end 501 may comprise aphase-locked-loop (PLL) 508, mixers 512 and 510, and a complex band-passfilter (BPF) 518. The BPF 518 may comprise a BPF with programmablecenter frequency.

The PLL 508 may comprise suitable circuitry, logic, and/or code and maybe utilized as a local oscillator to generate an in-phase (I) component514 and a quadrature (Q) component 516 of a local oscillator frequencyf_(LO). In addition, the PLL 508 may be adapted to provide fineresolution in output frequency. The mixers 512 and 510 may comprisesuitable circuitry, logic, and/or code and may be adapted to mix areceived signal f_(RX) with a local oscillator signal f_(LO) to generatean IF signal f_(IF). In this regard, the generated IF signal f_(IF) maybe expressed with the equation f_(IF)=±f_(RX)±f_(LO), where(f_(RX)−f_(LO)) may be the desired signal and (−f_(RX)+f_(LO)) may bethe unwanted image signal. Graph 500 illustrates the location on thefrequency spectrum of the desired signal f_(RX) 504, the localoscillator signal f_(LO) 502 and the image channel 506 corresponding tothe desired signal 504.

In operation, the received signal R_(X) 507 may be communicated to themixers 512 and 510. The PLL 508 may communicate the I component 514 tothe mixer 512 and the Q component 516 to the mixer 510 for mixing withthe received channel f_(RX) 507 to generate an IF signal f_(IF). Thegenerated IF signal may be filtered by the complex BPF 518 to passthrough the desired signal and filter out interference signals, such asadjacent and image channels. The BPF 518 with programmable centerfrequency may provide flexibility to avoid image interferers and/or maygive a performance advantage in RF environments with unequal channelseparation. The center frequency may be programmable from 300 kHz to 375kHz in 25 kHz steps, for example. After down conversion, the imagefrequency may be 600 kHz, 650 kHz, 700 kHz or 750 kHz, for example, awayfrom the desired signal, for example.

For example, graph 520 illustrates the desired signal 522 and thecorresponding image channel 524 after down conversion by the receiverfront-end 501. The image channel 524 may be rejected by utilizing theBPF 518, however, the image channel 524 may be in-band with the desiredsignal 522. In one embodiment of the invention, flexible tuning may beutilized with programmable IF frequency so that the image channelinterference signal after down-conversion and image rejection 506 may beshifted out-of-band, detected and rejected. For example, the imagechannel 506 may be shifted by shifting the IF frequency prior todown-conversion utilizing an offset by at most one-half the channelspacing. After down-conversion, the image channel 530 may be shiftedout-of-band and away from the desired signal 528, as illustrated bygraph 526. The out-of-band image channel 530 may be rejected a certainamount by the image-rejecting complex BPF 518 with a programmable centerfrequency.

FIG. 6 is a block diagram illustrating an exemplary high-side andlow-side injection in a front-end portion of an FM radio receiver, inaccordance with an embodiment of the invention. The FM radio receiverfront-end 601 may comprise a phase-locked-loop (PLL) 612, mixers 622 and624, and a switch 614. The PLL 612 may comprise suitable circuitry,logic, and/or code and may be utilized as a local oscillator (LO) togenerate an in-phase (I) component 616 and a quadrature (Q) component618 of a local oscillator frequency f_(LO). The PLL 612 may also beadapted to use high-side and low-side injection by flipping the LO-I 616and LO-Q 618 signal definitions via the switch 614, thereby swapping therelative phase difference between LO-I 616 and LO-Q 618. The mixers 622and 624 may comprise suitable circuitry, logic, and/or code and may beadapted to mix a received signal f_(RX) with a local oscillator signalf_(LO) to translate the RX signal to an IF signal f_(IF). In thisregard, the generated IF frequency f_(IF) may be expressed with theequation f_(IF)=±f_(RX)±f_(LO), where (f_(Rx)−f_(LO)) may be the desiredsignal and (−f_(RX)+f_(LO)) may be the unwanted image signal. The FMradio receiver front-end 601 may avoid strong image interferers byswitching from high to low side injection when the LO-I 616 and LO-Q 618signal definitions are swapped by the PLL 612. High side injection maybe represented by f_(LO)=f_(RF)+f_(IF), and low side injection may berepresented by f_(LO)=f_(RF)−f_(IF). In some instances, variable IF andHi-Lo side injection may be considered. For example, the combination ofvariable IF and programmable Hi-Lo side injection point may reduce thesignal level of the image interferer in a desired signal band. In thisregard, the quality of the received signal 620 may be enhanced.

Graph 600 illustrates the location on the frequency spectrum of thedesired signal f_(RX) 606, a low local oscillator signal f_(LO-LOW) 602,a high oscillator signal f_(LO-HI) 604, and the image channels 608 and610 corresponding to the desired signal 606 when f_(LO-LOW) 602 andf_(LO-HI) 604, respectively, are generated by the PLL 612.

In operation, the received signal R_(X) 620 may be communicated to themixers 622 and 624. The PLL 612 may communicate the I component 616 tothe mixer 622 and the Q component 618 to the mixer 624 for mixing withthe received channel f_(RX) 620 to generate an IF signal f_(IF). Graph626 illustrates the absolute frequency location of the desired signal630 and the in-band interferer signal 628 with low-side injection whenf_(LO-LOW) 602 is utilized for generation of the IF frequency.Similarly, graph 632 illustrates the absolute frequency location of thedesired signal 634 and the in-band interferer signal 636 with hi-sideinjection when f_(LO-HI) 604 is utilized for generation of the IFfrequency. In this regard, since interference signal 610 is weaker thaninterference signal 608, hi-side injection may be selected for reducinginterference signal after down-conversion. This may be achieved by, forexample, flexible FM tuning.

FIG. 7 is a block diagram illustrating I/Q phase and amplitudeadjustment in a front-end portion of an FM radio receiver, in accordancewith an embodiment of the invention. Referring to FIG. 7, the FM radioreceiver front-end 700 may comprise a phase-locked-loop (PLL) 702,mixers 706 and 708, a complex band-pass filter (BPF) 718, a delay block704, and gain adjustment block 710.

The PLL 702 may comprise suitable circuitry, logic, and/or code and maybe utilized as a local oscillator to generate an in-phase (I) component712 and a quadrature (Q) component 714 of a local oscillator frequencyf_(LO). The mixers 706 and 708 may comprise suitable circuitry, logic,and/or code and may be adapted to mix a received signal f_(RX) 716 witha local oscillator signal f_(LO) to generate an IF signal f_(IF). Inthis regard, the RX signal may be translated to frequencies expressedwith the equation f_(IF)=±f_(RX)±f_(LO), where (f_(RX)−f_(LO)) may bethe desired signal and (−f_(RX)+f_(LO)) may be the unwanted imagesignal. Due to mismatches, offsets, and/or design asymmetry within thereceiver front-end 700, the I/Q LO signal may have amplitude and/orphase errors. In these instances, the amount of image rejectionachievable may be determined by the I/Q non-idealities and thecharacteristics of the complex filter, for example. For example,referring to graph 720, a strong image interferer signal 724 may bein-band with a desired signal 722. The negative impact of the I/Q LOnon-idealities may be corrected by adjusting the relative phasedifference between the LO I- and Q-signals 712 and 714 utilizing thedelay block 704, and the relative amplitude difference between the IF I-and Q-signals utilizing the gain adjustment block 710. Referring tograph 726, the image interferer signal 730 is still in-band with thedesired signal 728. However, the image interferer signal 730 hasweakened compared to the interferer signal 724, due to the gain andphase adjustment within the receiver front-end 700.

FIG. 8 is a flow diagram that illustrates exemplary steps for processingof signals, in accordance with an embodiment of the invention. Referringto FIGS. 2A and 8, at 802, the FM receiver 222 may tune to a particularfrequency within a range of FM channels based on a frequency offset thatis less than one-half the channel spacing between neighboring allocatedFM channels within the range of FM channels. At 804, a frequency errormay be determined by the FM receiver 222 for the particular frequencywithin the range of FM channels. At 806, the FM receiver 222 may selecta local oscillator frequency for the tuning based on the frequencyoffset. At 808, the FM receiver 222 may generate an intermediatefrequency (IF) channel utilizing the particular frequency and theselected local oscillator frequency. The generated IF channel may bebetween neighboring channels selected from the range of FM channels. At810, it may be determined whether the particular frequency comprises anon frequency channel utilizing a frequency error. The frequency errormay be based on the frequency offset.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputer system, or in a distributed fashion where different elementsare spread across several interconnected computer systems. Any kind ofcomputer system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computer system with a computerprogram that, when being loaded and executed, controls the computersystem such that it carries out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

1. A method for processing signals, the method comprising: tuning to aparticular frequency within a range of FM channels based on an IFfrequency that includes an integer multiple of the channel spacingbetween neighboring allocated FM channels within said range of FMchannels, offset by at most one-half said channel spacing; anddetermining, utilizing a frequency error, whether said particularfrequency comprises an on frequency channel, wherein said frequencyerror is based on said IF frequency.
 2. The method according to claim 1,further comprising selecting a local oscillator frequency for saidtuning based on said IF frequency.
 3. The method according to claim 2,further comprising generating an intermediate frequency (IF) channelutilizing said particular frequency and said selected local oscillatorfrequency, wherein said generated IF channel is between neighboringchannels selected from said range of FM channels.
 4. The methodaccording to claim 1, further comprising determining said frequencyerror for said particular frequency within said range of FM channels. 5.The method according to claim 1, further comprising determining whethersaid particular frequency comprises an image channel based on saidfrequency error.
 6. The method according to claim 1, further comprising,if said particular frequency comprises an on frequency channel,determining signal strength for each of a plurality of FM channelsadjacent to said particular frequency.
 7. The method according to claim6, further comprising: selecting an FM channel from said plurality of FMchannels adjacent to said particular frequency, based on said determinedsignal strength for each of said plurality of FM channels; and tuning animage channel corresponding to said particular frequency to saidselected FM channel.
 8. The method according to claim 1, furthercomprising determining said frequency error for said particularfrequency utilizing a DC offset.
 9. The method according to claim 1,further comprising storing signal strength information for a pluralityof image channels corresponding to a plurality of on frequency channelsselected from said range of FM channels.
 10. The method according toclaim 9, further comprising tuning to at least one of said plurality ofon frequency channels based on said stored signal strength information.11. A machine-readable storage having stored thereon, a computer programhaving at least one code section for processing signals, the at leastone code section being executable by a machine for causing the machineto perform steps comprising: tuning to a particular frequency within arange of FM channels based on an IF frequency that includes an integermultiple of the channel spacing between neighboring allocated FMchannels within said range of FM channels, offset by at most one-halfsaid channel spacing; and determining, utilizing a frequency error,whether said particular frequency comprises an on frequency channel,wherein said frequency error is based on said IF frequency.
 12. Themachine-readable storage according to claim 11, further comprising codefor selecting a local oscillator frequency for said tuning based on saidIF frequency.
 13. The machine-readable storage according to claim 12,further comprising code for generating an intermediate frequency (IF)channel utilizing said particular frequency and said selected localoscillator frequency, wherein said generated IF channel is betweenneighboring channels selected from said range of FM channels.
 14. Themachine-readable storage according to claim 11, further comprising codefor determining said frequency error for said particular frequencywithin said range of FM channels.
 15. The machine-readable storageaccording to claim 11, further comprising code for determining whethersaid particular frequency comprises an image channel based on saidfrequency error.
 16. The machine-readable storage according to claim 11,further comprising code for determining signal strength for each of aplurality of FM channels adjacent to said particular frequency, if saidparticular frequency comprises an on frequency channel.
 17. Themachine-readable storage according to claim 16, further comprising: codefor selecting an FM channel from said plurality of FM channels adjacentto said particular frequency, based on said determined signal strengthfor each of said plurality of FM channels; and code for tuning an imagechannel corresponding to said particular frequency to said selected FMchannel.
 18. The machine-readable storage according to claim 11, furthercomprising code for determining said frequency error for said particularfrequency utilizing a DC offset.
 19. The machine-readable storageaccording to claim 11, further comprising code for storing signalstrength information for a plurality of image channels corresponding toa plurality of on frequency channels selected from said range of FMchannels.
 20. The machine-readable storage according to claim 20,further comprising code for tuning to at least one of said plurality ofon frequency channels based on said stored signal strength information.21. A system for processing signals, the system comprising: a singlechip having an integrated Bluetooth® radio and an integrated FM radiocomprising: at least one processor that enables tuning to a particularfrequency within a range of FM channels based on an IF frequency thatincludes an integer multiple of the channel spacing between neighboringallocated FM channels within said range of FM channels, offset by atmost one-half said channel spacing; and said at least one processorenables determining, utilizing a frequency error, whether saidparticular frequency comprises an on frequency channel, wherein saidfrequency error is based on said IF frequency.
 22. The system accordingto claim 21, wherein said at least one processor enables selection of alocal oscillator frequency for said tuning based on said IF frequency.23. The system according to claim 22, wherein said at least oneprocessor enables generation of an intermediate frequency (IF) channelutilizing said particular frequency and said selected local oscillatorfrequency, wherein said generated IF channel is between neighboringchannels selected from said range of FM channels.
 24. The systemaccording to claim 21, wherein said at least one processor enablesdetermination of said frequency error for said particular frequencywithin said range of FM channels.
 25. The system according to claim 21,wherein said at least one processor enables determination of whethersaid particular frequency comprises an image channel based on saidfrequency error.
 26. The system according to claim 21, wherein said atleast one processor enables determination of signal strength for each ofa plurality of FM channels adjacent to said particular frequency, ifsaid particular frequency comprises an on frequency channel.
 27. Thesystem according to claim 26, wherein said at least one processorenables selection of an FM channel from said plurality of FM channelsadjacent to said particular frequency, based on said determined signalstrength for each of said plurality of FM channels, and wherein said atleast one processor enables tuning an image channel corresponding tosaid particular frequency to said selected FM channel.
 28. The systemaccording to claim 21, wherein said at least one processor enablesdetermination of said frequency error for said particular frequencyutilizing a DC offset of an FM demodulator.
 29. The system according toclaim 21, wherein said at least one processor enables storing of signalstrength information for a plurality of image channels corresponding toa plurality of on frequency channels selected from said range of FMchannels.
 30. The system according to claim 29, wherein said at leastone processor enables tuning to at least one of said plurality of onfrequency channels based on said stored signal strength information.